Some wireless networks are centrally controlled, with a single device coordinating the operation of all of the devices in the network. This central coordinator provides instructions to each of the devices regarding transmission times, power levels, and the like. One example of this sort of network is a piconet using the proposed IEEE 802.15.3 standard.
In certain ad hoc networks, there may be no specific device that must be a coordinator, but rather one device may be chosen from among all of the available devices to perform the functions required of a network coordinator. And if this device leaves the network for any reason, another network device can take over the functions of a network coordinator.
Typically when a current network coordinator identifies a device more capable of performing network control functions or when the current network coordinator knows that it will be leaving a network, it will arrange to hand off the duties of a network coordinator to another device. In this way, the new coordinator will be able to step in and take over the duties of the current network coordinator as soon as the current coordinator leaves the network (or otherwise ceases to be able to function as a network coordinator). The new network coordinator can then continue to provide the remaining devices with their required instructions, keeping the network functioning properly.
However, the hand-off process requires that the current network coordinator know when it will be ceasing its network control function so that it can perform the hand-off process to the new coordinator. And this hand-off procedure requires a certain amount of lead time so that the current coordinator can provide instructions to the new coordinator, and so that the new coordinator can begin performing its network control functions.
Unfortunately in some circumstances the network coordinator does not have advanced warning that it will be unable to perform its network control duties. For example, if a network control device is quickly powered down (e.g., it suddenly loses its power supply) without performing a proper shut down procedure, or if a mobile device is moved out of the range of the other devices the device might not have adequate time to perform the necessary hand-off functions.
In such a case, the network would be deprived of a network coordinator and would ultimately collapse. Without receiving controlling instructions, individual devices would each eventually drop from the network until none were left. It might then be possible for one of the network devices to start a new network, which the other devices could then join. However, this would involve wasted time waiting for the old network to collapse and starting the new network. It also runs the risk that multiple devices will all try and start new networks as new network coordinators, and that they will try and start new networks using the same network identifier.